The present invention relates to a process and a device for automatically welding workpieces consisting of a certain number of tubular components which are cut and joined together by welding in order to form piping, in which process the component already joined by welding and the standardized separate component are welded, after positioning and securing by securing jaws, by means of a welding robot along the line of contact between the two workpieces to be joined.
It finds its main application in assemblies in the chemical and petrochemical industries, metal construction workshops and assembly workshops.
Automation of the welding process is currently possible in very many branches of industry, in particular in metal construction and the automobile industry. Automatic welding processes are also applied in chemical factories but their applications are limited to the production of relatively simple components which can still be manipulated manually.
There are three methods for automatically making a weld by means of a welding robot:
1) the workpiece is secured and the torch moves along the weld seam, during which the automaton performs a precise movement. Bodywork accessories are produced in this way in the automobile industry; PA1 2) the torch occupies a fixed position and the workpiece is able to perform the necessary movement, for example a revolution about a horizontal axis at a suitable speed; PA1 3) a combination of the above two methods. As a result of recent developments in electronics, open control systems which are easy to employ have now been commercialized, by means of which it is possible to synchronize the movements of the workpiece and the torch.
When welding piping, one is confronted with the problem of complicated programming for the movement of the torch, because the weld seam lies every time at various inaccessible points. A program has to be written for each seam.
On the other hand, the welding machine in which the torch occupies a fixed place and the workpiece is moved has the drawback that, if the piping is of unusual shape and dimensions, the workpiece is complicated to manipulate. The movement of the piping is different for each weld seam and consequently impossible to program.
The problem consists in proposing accessories for a suspension and/or welding machine, as well as in developing a welding method by means of which certain workpieces of complicated shape and dimensions can be produced automatically without any manual intervention using standardized elementary tubular components. The workpiece thus obtained may be manipulated and moved at any time without the acceptable limit values, imposed by the directives for the manual handling of loads and the manipulation of merchandise, being transgressed, in accordance with the Royal Decree of Aug. 12, 1993 relating to the manual handling of loads. This Royal Decree transposes into Belgian Law the fourth Special Directive, 90/269/EEC, of the Council of the European Communities of May 29, 1990 relating to the minimum health and safety regulations relating to the manual handling of loads involving risks, especially dorso-lumbar risks, for workers.